CERN(08 June 2009)-The CLOUD experiment - where particle physics meets climate science - starts getting ready to take data:

On CLOUD nine

The team from the CLOUD experiment - the world’s first experiment using a high-energy particle accelerator to study the climate - were on cloud nine after the arrival of their new three-metre diameter cloud chamber. This marks the end of three years’ R&D; and design, and the start of preparations for data taking later this year.

The CLOUD team will be able to recreate the conditions

of any part of the atmosphere inside the new chamber,

from the polar stratosphere to the low level tropics.

The link between cosmic rays and climate change is one that has been hotly debated over the past decade, grabbing the attention of the media. The idea revolves around the possibility that particles entering the atmosphere from space can affect cloud formation, which in turn affects the climate. But despite the controversy surrounding the theory, the central question – ‘do cosmic rays help create clouds?’ – has barely been tested in a laboratory before.

The new chamber arrives in the East Hall.

Once carefully cleaned the chamber will be turned

sideways onto its legs ready for the beam of ‘cosmic rays’.

The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment here at CERN will be one of the first experiments in the world directly to test the effect of cosmic rays on cloud formation under controllable laboratory conditions. The experiment’s three-metre diameter aerosol/cloud chamber arrived on Wednesday 20 May. This crucial piece of the experiment will be used to recreate carefully various conditions in the atmosphere.

The chamber is the culmination of three years’ research and design since the experiment was first approved in 2006. After being fitted with an array of sensitive analysing instruments, it will be carefully cleaned, tested and calibrated. The team hope to start collecting data later this year.

"I think the evidence for a link between reconstructions of past climate change and solar activity is too strong to ignore," explains Jasper Kirkby, Spokesperson for the CLOUD experiment. "There are a lot of observations showing that variations of the sun seem to be affecting the climate, but we don’t yet know what the mechanism for this is."

"The aim of CLOUD is to understand whether or not cosmic rays can affect clouds and climate, by studying the microphysical interactions of cosmic rays with aerosols, cloud droplets and ice particles." This is one of the possible mechanisms for solar-climate variability since the solar wind – the stream of charged particles ejected from the sun – varies over time and affects the intensity of the cosmic rays that reach the Earth.

"The whole process is well understood except for whether or not cosmic rays do indeed affect clouds. If that process can be established then I think solar-climate variability will very rapidly change from being a controversial subject to one with a lot of respectability. If, on the other hand, we rule out the process then this will allow us to focus on other mechanisms that might be causing the link," continues Kirkby.

A beam from the Proton Synchrotron is used to create a beam of ‘artificial cosmic rays’. These can be carefully controlled and aimed into the new chamber, which is bristling with sensors like spectrometers, ice-crystal detectors and CCD cameras. With the addition of a thermal housing and control system next year the team will be able to recreate the conditions of any part of the atmosphere inside the chamber, from the polar stratosphere to the low level tropics.

"We can carefully control what is inside the chamber, but we can also control the cosmic rays," say Kirkby. Being able to test under controllable conditions is what makes CLOUD different from atmospheric observations. "If you measure something directly in the atmosphere then you can never be certain what caused it as there are so many changing variables to take into account."

Cloud formation strongly depends on certain trace gases in the atmosphere, and their concentrations inside the chamber need to be controlled precisely. So one of the big challenges is to make the chamber as clean as possible, which has involved CERN experts who are used to dealing with ultrahigh vacuum components for the accelerators. "But even by CERN standards, the CLOUD requirements are challenging. We control the concentrations of certain gases to better than one part per trillion, which is 4-6 orders of magnitude below what is necessary for most particle physics liquid or gaseous detectors".

This is the first time a particle accelerator has been used to study atmospheric and climate science and CLOUD therefore lies at an intersection between several different disciplines. The team includes atmospheric physicists and chemists, solar physicists, cosmic-ray physicists and particle physicists.

"CLOUD has a world-class experimental team, bringing together the leading aerosol and cloud physicists in Europe and America", says Kirkby. "Working on an interdisciplinary experiment is certainly exciting. Particle physics and atmospheric physics tend to approach things differently - there is almost a cultural difference. Particle physicists are always happier to look at the simplest, most fundamental systems, whereas most atmospheric and climate physicists approach from one of the most complex systems possible – namely the atmosphere and climate."

In fact, the team come from such a variety of disciplines that the Universities of Geneva and Lausanne have initiated a sociological PhD project on CLOUD to observe how interdisciplinary collaborations work.

For more information please visit the CLOUD website: http://cloud.web.cern.ch/cloud/

The full-length video of Jasper Kirkby’s recent CERN colloquium ‘Cosmic rays and Climate’ is available here:

http://indico.cern.ch/conferenceDisplay.py?confid=5257

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CERN(08 June 2009)-Final electrical interconnections.

In Sector 3-4 the full length of the beam lines have been closed and work is currently ongoing to finish the final electrical interconnections. Once that is completed, work will start to close up the W bellows - the large accordion-shaped sleeves between two magnets - and preparations can start to cool the sector down.

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CERN (25 May 2009)The LHC quench protection system & The latest from the LHC...

The LHC quench protection system

The new quench protection system (QPS) has the crucial roles of providing an early warning for any part of the superconducting coils and busbars that develop high resistance, as well as triggering the switch-off of the machine. Over 2000 new detectors will be installed around the LHC to make sure every busbar segment between magnets is monitored and protected.

One of the major consolidation activities for the LHC is the addition of two new detectors to the quench protection system. A magnet quench occurs when part of the superconducting cable becomes normally-conducting. When the protection system detects an increased resistance the huge amount of energy stored in the magnet chains is safely extracted and ‘dumped’ into specially designed resistors. In the case of the main dipole chain, the stored energy in a single LHC sector is roughly the same as the kinetic energy of a passenger jet at cruising speed.

The first new detector is designed to monitor the superconducting busbars, including the joints between segments – the part that caused the incident in Sector 3-4 last September. The new system can measure the busbar resistance to about 1 nano-ohm (one billionth of an ohm) and will provide an early warning for any joint that develops high resistance.

"With this detector in place, we would have caught the ‘bad joint’ in Sector 3-4 two days earlier – safely in time to prevent any damage", explains Knud Dahlerup-Petersen from the Quench Protection team. In total, 2132 of these detectors will be installed around the machine, so that every busbar segment between the magnets will be monitored.

The second new detector protects against ‘symmetric quenches’. It was originally planned to add this second phase of the protection system during the first winter shutdown period. In February this year, however, it was decided that the system should be in place before the LHC restart. "So it has been a real effort to catch up, but our group (TE/MPE) had a lot of help from other groups, mainly TE/EPC and other departments, in particular PH and EN, and we’re now fairly confident that the whole system will be ready in time", says Petersen.

Symmetric quenches were only discovered in June last year during the campaign of training quenches in sector 5-6. When a magnet quenches, a symmetric quench can occasionally occur in the neighbouring magnets. It is caused by the heat transfer between the magnets, but it is particularly difficult to detect as the quench develops identically in both parts of the magnet coils which are used for the quench signal. The existing detection system compares the voltage signals from the two coils to detect a resistive build-up in either one. However if the quench develops in both at the same time, the two voltage signals remain the same, and the quench goes unnoticed.

The new protection system monitors the voltage across 4 adjacent dipoles (or 2 adjacent quadrupoles), allowing a symmetric quench to be detected and also provides a back-up detection method for ‘normal’ (asymmetric) quenches. However, the 4-magnet measuring system is based on digital quench detector technology, as opposed to analogue electronics used in the present QPS system. "It is notoriously difficult to find digital electronics that will not degrade in the high-radiation environment, so we had to choose the components carefully." Says Petersen. "We have now fully radiation-tested the first prototype, and we are basically ready to start mass production of the so-called SymQ detector board."

The thousands of new detector boards will be housed in 436 crates around the LHC. As the complex design lead to a relatively long R&D period there’s now not enough time to tender production out to an external company. Therefore, a production line for assembling of the complete protection units has been set up in a CERN workshop.

Another important measure taken is the consolidation of the network of Uninterruptable Power Supplies (UPS), designed and operated by EN/EL. The UPS provide power to all the essential parts of the machine, including the quench protection system, even if there is a problem with the mains grid. However, the UPS was not completely fail-safe as certain parts were not fully redundant. During the energy extraction, which takes up to 6 minutes in the dipole circuits, the magnet system remained unprotected in the event of a UPS failure. New cables have been laid and modifications applied to the UPS to make sure that the part of the UPS which powers the QPS systems is completely backed-up.

The latest from the LHC

New test diagnostics are being developed to measure the electrical resistance of the copper component of the superconducting busbars, specifically within the interconnections that join the busbars together (see previous update) The first test is very precise but requires local access to the interconnection, which therefore needs to be open. A second test has been developed that can be performed externally using voltage tap connections. This allows the resistance of a 30-40m segment to be measured without opening interconnections. The two methods have been checked to give consistent results and can be used to identify the interconnections with the highest resistances, which are subsequently repaired. In parallel simulations and laboratory tests are also being carried out. All dipole interconnections in the four sectors have been measured at room temperature. Work is ongoing to measure the quadrupole lines, which have much longer busbar segments. A further test is currently being developed to be performed at cryogenic, but non-superconducting temperatures, to allow the rest of the machine to be checked.

The installation work on the pressure release ports of the inner triplets magnets has now been completed.

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Cern 30 April 2009 The Latest from the LHC-Final magnet for the Sector 3-4 repairs

The Latest from the LHC

The 53rd and final magnet for the Sector 3-4 repairs was lowered into the tunnel on Thursday, 30 April, marking the end of repair work above ground.

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Ο 53ος και τελικός μαγνήτης για τον τομέα 3-4 επισκευάστηκε και κατέβηκε στη σήραγγα στις 30 Απριλίου (Πέμπτη) , χαρακτηρίζοντας το τέλος της εργασίας των επισκευών επάνω από το έδαφος.

Τωρα η δουλειά μεταφέρετε στο τούνελ

The final magnet, a quadrupole magnet designed to focus the beam, was lowered and transported to Sector 3-4 on Thursday last week. With all the magnets now underground, work in the tunnel will be focused on connecting the magnets together, while on the surface teams will be shifting their attention to replenishing the LHC’s supply of spare magnets.


Now we will split our ‘troop’ into two parts", explains Lucio Rossi, Deputy Head of the Technology Department. "The main group will be directly involved in the tunnel to ramp up with interconnection work as fast as possible. The second group will rebuild our stock of spare magnets."

In total 53 magnets were removed from Sector 3-4. Sixteen magnets that sustained minimal damage were refurbished and put back into the tunnel. The remaining 37 were replaced by spares, depleting the number of reserve magnets to nearly zero. As Rossi explains, the last magnet to be lowered "is really one of the last magnets of our stock - we could say it is the spare of the spares."

"Most of the spare magnets were ready to be ‘cryostated’ - put onto the cryogenic cover - and tested before going down to the tunnel. The final magnet, however, was still unfinished. "One of the reasons it took so long is because the ‘cold mass’ – the magnet itself - still had to be completed", confirms Rossi.

Once all interconnection work is completed in the tunnel, work will continue on the surface to repair the remaining damaged Sector 3-4 magnets to be kept as spares. By the end of the year, 15 should have been completed.

Δείτε και το σχετικό Βιντεο εδώ

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##Στην δεξιά στήλη υπάρχει το εικονίδιοαν πατήσετε τα υπογραμμισμένα γράμματα "Πάτα εδώ για να δεις ολες τις δημοσιεύσης στα Ελληνικά " θα μεταφραστεί όλο το blog στα Ελληνικά αλλα με κάποια σφάλματα στα βίντεο ή σε κάποιες λέξης ορολογίας.Δεν είναι και η καλύτερης ποιότητας μετάφραση αλλά βοηθάει στην κατανόηση##

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A new LHC 'video και μερική επεξήγηση

A new LHC 'video news' is now out on CERN's YouTube channel:

Δείτε το βίντεο στο YouTube.Αν και είναι στα αγγλικά και κάποιοι να μην καταλαβαίνετε τα πάντα η εικόνα από μόνη της λέει πολλά.



Με λίγα λόγια δείχνει την επιχείρηση που θα πάρουν τους μαγνήτες και τους αγωγούς(είναι αυτοι οι μπλε "σωλήνες" που στην πραγματικότητα λέγονται δίπολα-dipole) που είχαν την διαρροή πέρυσι τον Σεπτέμβριο( στις 19 του μήνα) και θα το κατεβάσουν κάτω από την γη(στο δακτυλίδι που έχει σχηματίσει ο επιταχυντής περιμέτρου 27 χιλιομέτρων) με έναν τεράστιο γερανό[πάνω από 100 μέτρα κάτω από το έδαφος θα φτάσει το κομμάτι αυτό..] Το κάθε κομμάτι ζυγίζει περίπου 33 Τόνους έχει 50 μέτρα μάκρος και είναι "γεμάτο" με την τελευταία τεχνολογία που υπάρχει στον πλανήτη (βίντεο 4,31 λεπτά και εξής)

Επίσης λέει ότι στο Cern θα αναπτυχθεί για πρώτη φορα τόσο ισχυρό μαγνητικό πεδίο, δηλαδη περίπου 8 Tesla και τόσο χαμηλή θερμοκρασία 1,9 βαθμούς ( Κέλβιν) πάνω απο το απόλυτο μηδεν δηλαδή -271,1 Βαθμοί Κελσίου(εμεις στο σώμα μας έχουμε 36,6 βαθμούς Κελσίου ή αλλιώς 309,6 βαθμούς Κέλβιν..).Δεν πρέπει να ξεχάσουμε οτι η χαμηλότερη θερμοκρασία στο σύμπαν μπορεί να φτάσει τους -273 Κελσίου(C) δηλαδή τους μηδέν Κέλβιν(μηδέν Κελβιν= απόλυτο μηδέν)..Γιαυτό άλλωστε δεν χρησιμοποιούν παγάκια(!!) για να ψύξουν τους αγωγούς αλλα το στοιχειο ήλιο(Ηe) σε υγρή μορφή.

Τέλος τα μεγάλα αυτά κομμάτια του αγωγού θέλουν περίπου 1 ώρα για να μεταφερθούν με το ειδικό αμαξίδιο σε κάθε τομέα του επιταχυντή.Και τα κομμάτια που πρέπει να κατέβουν στο τούνελ είναι πολλά..

Πάντως δουλεύουν με πολύ μεγάλη ταχύτητα αφού κατάφεραν και τους εφτιαξαν και τους κατέβασαν όλους σε 8 περίπου μήνες.

Geneva, 30 April 2009-Final LHC magnet goes underground

Final LHC magnet goes underground

Geneva, 30 April 2009. The 53^rd and final replacement magnet for CERN's¹ Large Hadron Collider (LHC) was lowered into the accelerator's tunnel today, marking the end of repair work above ground following the incident in September last year that brought LHC operations to a halt. Underground, the magnets are being interconnected, and new systems installed to prevent similar incidents happening again. The LHC is scheduled to restart in the autumn, and to run continuously until sufficient data have been accumulated for the LHC experiments to announce their first results.

"This is an important milestone in the repair process," said CERN's Director for Accelerators and Technology, Steve Myers. "It gets us close to where we were before the incident, and allows us to concentrate our efforts on installing the systems that will ensure a similar incident won't happen again."

The final magnet, a quadrupole designed to focus the beam, was lowered this afternoon and has started its journey to Sector 3-4, scene of the September incident. With all the magnets now underground, work in the tunnel will focus on connecting the magnets together and installing new safety systems, while on the surface, teams will shift their attention to replenishing the LHC's supply of spare magnets.

In total 53 magnets were removed from Sector 3-4. Sixteen that sustained minimal damage were refurbished and put back into the tunnel. The remaining 37 were replaced by spares and will themselves be refurbished to provide spares for the future.

"Now we will split our team into two parts," explained Lucio Rossi, Deputy head of CERN's Technology Department. "The main group will carry out interconnection work in the tunnel while a second will rebuild our stock of spare magnets."

The LHC repair process can be divided into three parts. Firstly, the repair itself, which is nearing completion with the installation of the last magnet today. Secondly, systems are being installed to monitor the LHC closely and ensure that similar incidents to that of last September cannot happen again. This work will continue into the summer. Finally, extra pressure relief valves are being installed to release helium in a safe and controlled manner should there be leaks inside the LHC's cryostat at any time in the machine's projected 15-20 year operational lifetime.

CERN is publishing regular updates on the LHC in its internal Bulletin, available at www.cern.ch/bulletin, as well as via twitter and YouTube at www.twitter.com/cern and www.youtube.com/cern

1. CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

Cern 16 April 2009 The last repaired dipole for Sector 3-4 has been lowered into the LHC tunnel.

The Latest from the LHC
The last repaired dipole for Sector 3-4 has been lowered into the LHC tunnel.

© CERN

Watch the video Here !

Δες το Βίντεο Εδώ !


The 39th and final repaired dipole magnet was lowered into Sector 3-4 and installed on Thursday 16 April. This is the last of the LHC’s easily recognizable 15-metre-long blue superconducting dipoles required for the 3-4 repair. Only two more Short Straight Sections (SSS) remain to be installed in 3-4.

Since the start of the repair work in Sector 3-4, the Vacuum Group have been cleaning the beam pipes to remove metallic debris and soot created by the short circuit last September. Firstly all 4800 m of the beam pipes in Sector 3-4 were surveyed cm by cm to document the damage before the cleaning work started. The cleaning process involves passing a brush through the pipe to clean the surface mechanically, followed by a vacuum to remove any debris both inside and outside the beam pipe. This procedure is repeated ten times, followed by a final check with an endoscopic camera. So far 68% has been completed.

Work to install the new pressure release ports has now started in the areas outside the arc sections – in particular on the inner triplets (the focusing magnets either side of the collision point). The ports have been slightly modified to fit the geometry of these magnets.

A new test has been developed to measure the electrical resistance of the connection joining the ‘busbars’ of the superconducting magnets together. The busbar consists of a superconducting cable surrounded by a larger copper block known as a ‘stabilizer’. The copper helps to conduct electricity in the event that part of the superconducting cable becomes normally-conducting (for example during a quench). The new test allows the electrical continuity of this copper part to be checked. This provides another important quality control safety check for the electrical connections.

Cern 24 April 2009-T2K neutrino beam starts operation

News: 24 April 2009

T2K neutrino beam starts operation

The Tokai to Kamioka (T2K) neutrino oscillation experiment confirmed the first neutrino beam yesterday. The team verified the neutrino beam by observing the muons produced by the proton beam in the neutrino facility at the Japan Proton Accelerator Complex (J-PARC).

The T2K project, which is a CERN recognized experiment, involves sending a neutrino beam from J-PARC at Tokai to the Super-Kamiokande neutrino observatory some 300 km away. In a similar manner to the neutrino beam sent from CERN to experiments in Gran Sasso (Italy), the T2K experiment hopes to increase our understanding of neutrino mass by looking at oscillations between different types of neutrinos.

In 2005 CERN donated a magnet originally built for the UA1 detector to the Japanese High Energy Accelerator Research Organization (KEK) for use in the T2K experiment. More details available here.

Read the full KEK press release here:
http://www.kek.jp/intra-e/press/2009/J-PARCT2K.html

Cern 23 April 2009-First beam in the SPS after the winter shut-down

News: 23 April 2009

First beam in the SPS after the winter shut-down

The first beam was injected today from PS into SPS. After some earlier repairs to the ejection and injection components the teams managed to get first beam exactly on schedule.

Cern 6 April 2009-PS has beam ahead of schedule

Ανακοινώθηκε με χαρά!!!





The Latest from the LHC

The campaign to install the new helium pressure release system is progressing well. The first sector to be fully completed is 5-6, with all 168 individual pressure release ports installed. These ports will allow a greater rate of helium escape in the event of a sudden increase in pressure of the insulation vacuum. To install them the teams had to initially open the ‘W bellows’ – the large accordion-shaped sleeves that cover the interconnections between two magnets. Now that all the pressure release ports have been fitted, these ‘W bellows’ can start to be closed up again – marking the end of the consolidation work in 5-6. Preparations are starting to be made to cool the sector down: this week the first three ‘vacuum sub-sectors’ have been sealed. Each sub-sector is a 200 metre-long section of the insulating vacuum chamber that surrounds the magnet cold mass. Once sealed the sub-sector is pumped out and tested for leaks.

The damaged area of Sector 3-4 is buzzing with activity. Teams are working through the night and on weekends to install the replacement magnets at a rate of 6-7 per week. With more and more magnets installed and aligned, the pace of the work to join all the various connections from each magnet to its neighbours, has increased sharply over the past few weeks: for example, the soldering of electrical joints has gone up from 2 to 8 interconnects per week within a fortnight.

Work to fit the replacement magnet in Sector 1-2 has been completed. This magnet replaces one that was found to have high internal resistance and was previously removed (see previous update - http://cdsweb.cern.ch/record/1158758?ln=en).

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News: 6 April 2009
PS has beam ahead of schedule

Protons are circulating again in the PS after the winter shut-down: Saturday morning at 2:14, a few days ahead on the official schedule, the PS received its first beam of protons of the year just a few days after the LINAC 2 and the PS Booster.

After having been partially refurbished, the injector chain is performing well and the non-LHC physics programme is progressively restarting. The next in the chain is the SPS, expected to re-start in the week after Easter.

* View the 2009 Injector Accelerator Schedule on the BE department website (PDF format)


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